Manufacture of filamentary material from copolymers of acrylonitrile and vinylidene chloride



United States Patent MANUFACTURE OF FILAMENTARY MATERIAL FROM COPOLYMERS OF ACRYLONITRILE AND VINYLIDENE CHLORIDE John Downing and James Gordon Napier Drewitt, Spondon, near Derby, England, assignors to British Celanese Limited, a corporation ofGreat Britain No Drawing. Application December 20, 1952, Serial No. 327,169

Claims priority, application Great Britain January 10, 1952 7 Claims, (CI. 18-54) This invention relates to the manufacture of filamentary material, including single filaments, multi-filament twisted and untwisted yarns, tow, bristles and the like,

having a basis of an acetone-soluble copolymer of acrylonitrile and vinylidene chloride.

In U. S. application SerialNo. 269,608, filed February 1, 1952, now Patent No. 2,679,450, there is described the production of textile material by spinning acetone solutions of acetone-soluble copolymers of acrylonitrile and vinylidene chloride cqntaining 2050% by weight of acrylonitrile, stretching the filamentary material so obtained,

, and then heating it to a temperature above 150 C., first under tension and then while allowing it to shrink. The filamentary material is preferably made by dry spinning the copolymer solution, but if desired wet spinning may be employed, using as coagulant an aqueous bath which preferably contains a solvent or swelling agent for the copolymer, for example acetone or another lower aliphatic ketone.

According to the present invention we make filamentary material by extruding an acetone solution of an acetone-soluble copolymer of acrylonitrile and vinylidene chloride into a coagulating bath of which at least 83% (by weight) consists of one or more hydrocarbons. The

material so produced is preferably subsequently stretched mixtures of aliphatic hydrocarbons boiling within the range 150-300 C., commercial kerosene being very satisfactory. The hydrocarbons may contain up .to about 20% of their weight (corresponding to about 17% by weight of the coagulating bath as a whole) of a solvent or swelling agent for the copolymer, for example acetone or another lower aliphatic ketone, but it is usually des'irable to keep the content of the solvent or swelling agent in the bath, including that derived from the spinning solution, below about 10% and especially below about 6% of the weight of the hydrocarbons.

The copolymer from which the filamentary material is made preferably contains 2050% by weight of acrylonitrile, and in order that it shall be soluble in acetone it is necessary that the unit structures therein derived from the respective monomers should be fairly regularly distributed throughout the polymer chain. Copolymers satisfying this condition may be made for example by copolymerising vinylidene chloride and acrylonitrile in an aqueous medium in which the monomers are emulsified or suspended, the amount of water present atthe beginning of the process being between 5 and 10 times the ICC total weight of the two monomers. The water preferably contains a small amount of an emulsifying agent, for instance an anion-active surface-acting agent such as a salt of a sulphated long chain fatty alcohol, and also a polymerisation catalyst, preferably a water-soluble compound capable of forming free radicals, especially ammonium or an alkali metal persulphate. The polymerisation may be carried out at temperatures a little above room temperature, for example at about 35 50 C., but other temperatures can be used; naturally the lower the temperature the slower is the reaction. More detailed information about the production of the copolymers will be found in British specification No. 643,198 of British Celanese Limited.

The copolymer may be in solution in substantially pure acetone or in acetone containing a small proportion, e. g. up to a total of 5% or 7.5%, of water and/or and alcohol of boiling point below 120 C., especially methyl alcohol, ethyl alcohol or isopropyl alcohol. Commercial acetone containing about 25% of water is suitable, with or without a small proportion of an alcohol of boiling point below 120' C. The solution may with advantage be made by mixing the copolymer with the solvent in a mixing machine having a kneading action, e. g. a Werner-Pfieiderer mixer. The concentration of the copolymer in the spinning solution is preferably about 1532% and especially about 17-25%, the precise con centration in any particular case being so chosen as to give a suitable spinning vicosity at the temperature at which the solution is to be extruded. This may be room temperature or a higher temperature, for example about 60-85 C. The coagulating bath also may be at room temperature or at a higher temperature, e. g. up to about C.

The coagulating bath may flow in the same direction as or in the opposite direction to the direction of travel of the filamentary material, or it may flow across the path of the material or be relatively quiescent. During its passage through the bath the filamentary material may with advantage be given a degree of draw-down, e. g. by about 20-150% of its original length, under conditions such that the necessary tension in the yarn is not carried back the point of extrusion but is localised in the yarn by means of snubbing pins.

After leaving the bath the material may be freed from the hydrocarbon coagulating liquid, e. g. by washing either with a more volatile .hydrocarbon, for example petrol, or with some other liquid which will dissolve the hydrocarbons of the bath without affecting adversely the properties or structure of the filamentary material, e. g.

an ether such as diethyl ether. The material may then be dried, for instance in a current of warm air. Usually however it is advantageous to pass the material to a subsequent stretching operation while it still carries residual coagulant.

The filamentary material may be orientated by stretching at a temperature above C. and preferably between about and 210 C., especially about 205 C. For example the material may be stretched while or immediately after passing over a smooth heated surface, which may be stationary or may be the surface of a rotating roll or the like, and which is kept at a suitable temperature by any appropriate heating means; or the material may be heated by means of an inert fluid, for instance hot air, a mineral oil, a glycol or glycerol, or by radiation. For example it may be passed through a bath of the same hydrocarbon or hydrocarbon composition as that used as coagulant, provided the hydrocarbon boils at a sufficiently high temperature. The material maybe stretched by 50-1000% or more of its length. t

Following the stretching, the filamentary material may 'a roll immersed in a heating fluid. material is to be heated by any means involving direct about 3-7 minutes.

be set or annealed by heating it at approximately concontact with a heating fluid, there may be used one of the fluids specified above in connection with the stretching step. Quite a short treatment is sufiicient to set the material, and indeed is to be preferred; for instance at temperatures between about 165 and 190 C. 2-5 minutes is usually sufficient, while even at temperatures down to about 150 C. minutes will sufiice.

The set filamentary material may then be heated under .little or no tension to a temperature of at least 150 -C. for about 2 minutes or more; if the greatest possible degree of thermal stability is required the material may .be heated either to the setting temperature or a higher temperature up to about 195 or 200 C., or to a temperature not more than about 25 C. below the setting temperature (but always above 150 C.) preferably for For example, if setting. has been carried out at 190 C., the material may be subsequently heated to l70l90 C. During this step the material may either be allowed to shrink freely, or may be subjected to a degree of tension such that the shrinkage is controlled, but preferably amounts to at least half of the shrinkage under free conditions. The material may be heated by methods similar to those described for the 1 similarly if the material is treated as a running yarn or the like, the take-up rate should be suitably lower than the feed rate.

Although the copolymers used in the process of the invention have good colour-stability, it may sometimes be found that a certain degree of darkening takes place,-

especially at temperatures in the neighbourhood of 190"- 200 C. Any such tendency may be greatly reduced or even eliminated by incorporating in the filamentary material a substance capable of acting as a stabiliser, for example a substance which when incorporated in polyvinylidene compounds acts as an anti-oxidant and/or is capable of taking up hydrogen chloride and chlorine. Examples of stabilisers are certain compounds of lead, zinc, tin and other metals, for instance lead orthosilicate, phthalate, or stearate, zinc stearate, dibutyl tin laurate or stearate, di-alkyl di-alkoxy compounds of tin such as dibutyl dibutoxy tin, calcium aceto-acetate and stearate, cadmium 2-ethyl-hexoate, barium stearate, and mixtures of cadmium and barium salts; other stabilisers include epoxides, e. g. epoxy-propyl ethers of bis-phenols such as 4,4--bis-(2,3-epoxypropoxy)-diphenyl, endo-methylene tetra-hydrophthalic acid, l:l'-diphenyldiethyl ether, ma-

leic acid and derivatives thereof, butyrolacetone, 2,3,5- trichloro-2'-hydroxy-benzophenone, 2,2-dihydroxy-benzophenone, alkaline earth metal salts of chlorinated hydroxy-benzophenones, phenyl salicylate (salol) and alkylphenyl salicylates such as t-butyl-salol. Quite a small proportion of stabiliser is suflicient, e. g. 0.l-2% of the weight of the copolymer. The stabiliser may be incorporated at any convenient stage; for example it may.

be added to the spinning solution, or it may be present during the actual formation of the copolymer.

Example 19 parts by weight of an acetone-soluble copolymer of acrylonitrile and vinylidene chloride containing 25% by weight of acrylonitrile and 75% by weight of vinylidene chloride was mixed in a Werner-Pfleiderer mixer with parts by weight of a commercial acetone containing 2% of water until a clear solution had been formed. This solution was filtered and extruded as filaments through a spinning jet having 60 holes each of 0.05 mm. diameter into a bath of kerosene at 30 C. The length of the path of the filaments through the bath was 16 inches, and the content of acetone in the bath was not allowed to exceed 5% of the weight of the kerosene. I

After leaving the bath the filaments, while still carrying residual kerosene on their surfaces, were stretched by 600% of their length while in contact with a metal surface at 200 C. The stretched filaments had a tenacity of 3.1 grams/denier and an extension at break of 7%.

The extension at break, and also the dimensional stability, of the stretched filaments could be improved by first setting and then relaxing them. To set them the filaments were heated to 170 C. for 4 minutes while held taut against shrinkage, and to relax them the set filaments were heated to 170 C. for a further 6 minutes while free to shrink. The set and relaxed filaments had a tenacity of 2.7 grams/denier and an extension at break of 15%, and also had a good appearance and handle.

Filamentary material could be made in the same Way from other acetone-soluble copolymers of acrylonitrile and vinylidene chloride, for example a copolymer containing 45% by weight of acrylonitrile and 55% by weight of vinylidene chloride.

The incorporation in the copolymer of 1% of its weight of dibutyl tin laurate or another of the stabilisers mentioned above was advantageous in view of the high temperatures at which the filaments were stretched.

Having described our invention what we desire to secure by Letters Patent is:

1. Process for the manufacture of filamentary material, which comprises extruding an acetone solution of an acetone-soluble binary copolymer of acrylonitrile and .vinylidene chloride into a coagulating bath of which at least 83% by Weight consists of aliphatic hydrocarbon material.

2. Process for the manufacture of filamentary material, which comprises extruding an acetone solution of an acetone-soluble binary copolymer of acrylonitrile and vinylidene chloride into a coagulating bath of which at least 83% by weight consists of aliphatic hydrocarbon material boiling within the range of -300 C.

3. Process for the manufacture of filamentary material, which comprises extruding an acetone solution of an acetone-soluble binary copolymer of acrylonitrile and vinylidene chloride into a coagulating bath of which at least 83% by weight consists of aliphatic hydrocarbon material and which contains also materials having at least a swelling action on the polymer in amount at most 10% of the Weight of the hydrocarbon material, including acetone from the solution of the copolymer.

4. Process for the manufacture of filamentary material, which comprises extruding an acetone solution of an acetone-soluble binary copolymer of acrylonitrile and vinylidene chloride into a coagulating bath of which at least 83% by weight consists of aliphatic hydrocarbon material and which contains material having at least a swelling action on the polymer in amount at most 6% of the weight of the hydrocarbon material, including acetone from the solution of the copolymer.

5. Process for the manufacture of filamentary material, which comprises extruding an acetone solution of an acetone-soluble binary copolymer of acrylonitrile and vinylidene chloride, containing 20 to 50% of acrylonitrile, into a coagulating bath of which at least 83% by weight consists of aliphatic hydrocarbon material.

6. Process for the manufacture of filamentary material, which comprises extruding an acetone solution of an acetone-soluble binary copolymer of acrylonitrile and vinylidene chloride, containing 20 to 50% of acrylonitrile, into a coagulating bath of which at least 83% by weight consists of aliphatic hydrocarbon material and which contains material having at least a swelling action on the polymer in amount at most 6% of the weight of the hydrocarbon material, including acetone from the solu-.

material and subsequently stretching the filamentary ma terial at temperatures above 120 C. to increase its tenacity.

References Cited in the file of this patent UNITED STATES PATENTS 2,515,206 Finzel et a1. July 18, 1950 2,531,406 DAlelio Nov. 28, 1950 2,679,450 Hampson et a1. May 25, 1954 FOREIGN PATENTS 643,198 Great Britain Sept. 15, 1950 

1. PROCESS FOR THE MANUFACTURE OF FILAMENTARY MATERIAL, WHICH COMPRISES EXTRUDING AN ACETONE SOLUTION OF AN ACETONE-SOLUBLE BINARY COPOLYMER OF ACRYLONITRILE AND VINYLIDENE CHLORIDE INTO A COAGULATING BATH OF WHICH AT LEAST 83% BY WEIGHT CONSISTS OF ALIPHATIC HYDROCARBON MATERIAL. 